title: Thermal changes of the crystal structure and the influence of thermo-chemical annealing on the optical properties of YbAlO3 crystals.
abstract: The paper presents experimental results of investigations on the influence of temperature and thermo-chemical annealing on the structural and optical properties of YbAlO(3) crystals. Thermal behaviour of the crystal structure has been studied in the temperature range of 19-1173 K by means of in situ high-resolution x-ray powder diffraction using synchrotron radiation. Lattice expansion of YbAlO(3) displays a strongly anisotropic character: the relative expansion along the b direction is about two times smaller than that along the a and c axes. The influence of thermo-chemical annealing in oxidizing and reducing atmospheres has been studied by means of in situ optical spectroscopy. The increase of the absorption in the range of 300-600 nm during annealing in an oxidizing atmosphere as well as its bleaching during reduction has been observed in the temperature range 700-1000 K. The oxidation and reduction kinetics have been analysed by means of mathematical models taking into account diffusion and the quasi-chemical reaction of the defect centres.
authors.affiliation: Lviv Polytechnic National University, Bandery Street 12, 79013 Lviv, Ukraine.
authors.forename: O
authors.initials: O
authors.lastname: Buryy
authors.forename: Ya
authors.initials: Y
authors.lastname: Zhydachevskii
authors.forename: L
authors.initials: L
authors.lastname: Vasylechko
authors.forename: D
authors.initials: D
authors.lastname: Sugak
authors.forename: N
authors.initials: N
authors.lastname: Martynyuk
authors.forename: S
authors.initials: S
authors.lastname: Ubizskii
authors.forename: K D
authors.initials: KD
authors.lastname: Becker